SEDIMENT ASSESSMENT

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SEDIMENT ASSESSMENT MANAGEMENT FOR DAM REMOVAL
PROJECTS

• Joe Rathbun
• Michigan Dept. of Environmental Quality
• Water Bureau
• 517-373-8868
• rathbunj_at_michigan.gov

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Outline

• Basic Concepts
• Sample Collection
• Survey design
• Grab and core sampling
• Effects Assessment
• Toxicity
• Bioaccumulation
• Sediment quality criteria
• Sediment Management Options

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Sediment Assessment Framework
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Sediment Management Framework
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Basic Concepts Sediment Transport

• Rivers do 2 things very well
• Move water
• Move sediment
• Most sediment transported during floods

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Basic Concepts Reservoirs are Sediment Traps

• Many trap 95 of the sediment that enters them
  from upstream
• Large sediment particles form deltas at upstream
  end
• Small sediment particles transported farther into
  reservoir

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Basic Concepts Issues with Contaminated
Sediments

• Direct toxicity to organisms
• Acute
• Chronic
• Bioaccumulation in organisms
• Alter benthic community
• Contaminate overlying water
• Affect disposal of dredged material

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Basic Concepts Contaminant Distribution

• ? grain size ? contaminant concentration
• Silt ? TOC, for organics ( metals)
• Clay ? binding sites for metals
• Grain size distribution predictable
• Upper impoundment large particles
• Lower impoundment fines

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Organic ContaminantsSediment vs. Water
Concentrations

• Depending on contaminant polarity, solubility,
  etc.
• Sediment gt water by factor of 1,000 to 10,000,000

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Almost always have to sample

• Because of unexpected historic contaminant
  sources
• Brick factories Cd, Pb, Ni, Ba, Se, Co
• Orchards tobacco fields As, Hg
• Tanneries Cd, Cr, As, Hg
• Coal gasification plants PAHs, metals
• Glass factories As, other metals
• Cemeteries Pb, As, Hg
• Dye manufacturers metals

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Sampling Survey Design

• First step in sampling
• Extremely important to data quality
• Sediment quality data are easy to collect but
  difficult to interpret unless obtained using a
  well-designed survey

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Sampling Survey DesignField vs. Lab
Heterogeneity

• Sources of data variability
• In-situ heterogeneity, in the field
• Collection biases inaccuracies
• Lab biases inaccuracies
• PCBs in soil (EPA, 1992)
• Lab lt 1 of data variability
• Location of sample 92 of data variability

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Simplest CaseSmall DamRural AreaNo Money

• Minimum data required
• Demonstrate lack of upstream sources
• Find silt deposits establish thickness
• Collect minimal number of samples
• 1 from each silt deposit, combine?
• Analyze for organics metals
• Compare to sediment quality criteria
• Sample benthos?

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Preferred Survey Design Process

• Establish study objectives, evaluate existing
  data, etc.
• Conduct reconnaissance survey
• Refine study objectives
• - Choose minimum number of stations that are
  representative of study area
• Conduct definitive survey

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Reconnaissance Survey

• Objectives
• Sampling access
• Sample collectability
• Qualitatively assess nature and extent of
  contaminated deposits
• Equipment
• Probing rod
• Small grab or core sampler
• Equipment for hydrographic survey
• GPS

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Reconn. Survey Mud Music ?

• Use hollow metal tube to identify sediment type
• Rock bounce clang
• Clay bounce silent
• Gravel crunch
• Silt silent, penetration
• Sand silent, no penetration

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Definitive Survey

• Objective
• Quantitatively establish magnitude and extent of
  contamination
• Equipment
• Grab or core samplers
• GPS
• Largely the same as reconn

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Definitive Survey Components

• Sampling design
• Sample collection technique(s)
• Sample analysis technique(s)
• Field and lab QA/QC
• Data interpretation
• Data mapping, volumetric calculations
• Modeling (?)

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Sampling Design

• What samples will be collected
• Whole sediment
• Elutriate
• Pore water
• How many samples will be collected
• Where samples will be collected
• How samples will be collected
• (When samples will be collected)

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Sampling Design How Many?

• Statistical calculations, with existing data
• n Variance
• Mean2 x Precision2
• - Requires historic data set
• - Really only appropriate for data from a single
  station!

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Sampling Design How Many?

• Calculated n is the number of samples that
  yields an overall mean concentration for the
  entire study area
• Sometimes want to identify hot spots, not average
  conditions

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Sampling Design How Many?

• Geostatistical models
• Elipgrid-PC
• Design of sampling grids
• Probability of locating hot spots
• Hot spot size, shape, orientation, grid spacing
  ( number of samples)
• http//dqo.pnl.gov/software/elipgrid.htm

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Elipgrid Example

• Canals on Lake St. Clair (MI)
• Surface area 233,000 ft2 21,700 m2
• - About 6 football fields
• Square grid
• 95 confidence
• Circular hot spot
• Calculate how many samples for different hot spot
  sizes

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Elipgrid Example

• Hot Spot Radius (m) Samples
• 1 7,787
• 5 312
• 10 78
• 15 35
• 20 20
• Often not happy with results!

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Sampling Design Where?

• Objective of the study
• Cost-effectiveness
• Use Elipgrid-PC
• Patterns of sediment contamination variability
• Practical considerations

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Simple Random Sampling
Flow
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Systematic Grid Sampling
Flow
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Subjective Sampling
Flow
Outfall
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Stratified Random Sampling
Gravel Bar
Flow
Silt Bar
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Some Sampling Design Guidance

• Contaminant distribution
• Random uniform
• Known strata
• Known hot spots
• Linear trends, or mapping important

• Recommended strategy
• Random sampling
• Stratified random sampling
• Subjective sampling
• Systematic grid sampling

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Sample Collection

• Grab samplers
• Core samplers

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Grab Sampling

• More recent sediments
• Mixed, mobile surface layer
• Biologically active zone

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Grab Samplers

• Require smaller sampling vessels
• Changing sediment composition variable
  penetration depths
• Silt gt sand gt gravel or clay
• Watch for buried sampler in soft sediments

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Ekman Grab Sampler
(Kahl Scientific Co.)
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Ekman in dugout canoe
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Ponar sampler
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Ponar Sampling in Whaler
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Van Veen Grab Sampler
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Grab Sampling is Dirty Work!
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Capacity of Grab Samplers

• Ekman 3.5 L
• Petite Ponar 2.4 L
• Standard Ponar 8.2 L
• Van Veen 24 L

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Core Sampling

• Recent to older sediments
• Stratified, less mobile deposits
• Aerobic ? anaerobic sediment
• Influences metal nutrient availability

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Core Samplers

• May distort sediment column (smearing,
  compression) or not sample completely (rodding)
• May require larger sampling vessels
• Changing sediment composition variable
  penetration depth
• Silt gt sand gt gravel or clay

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Core Sampler Types

• Hand corers
• Cores a few feet long, 2 diameter
• Shallow water
• Gravity corers, piston corers, etc.
• Cores lt 5 long
• Deep water
• Vibrocorers
• Cores up to 20 long, 4 diameter
• Deep water (gt 1,000)

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Hand-coring
Core Tube
Plastic tube drive in with fence post driver or
sledge
Cant drive in farther than can be pulled out by
hand, or with small winch
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Hand-coring
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Hand-coring
Subsample sleeve
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Gravity Corer

• Balcheck corer
• Requires winch
• 50 lbs.
• Core a few feet long, 2-3 diameter

(Wildlife Supply Co.)
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Vibrocore Sampling

• Rossfelder www.rossfelder.com
• Rossfelder P-3 or P-5 vibrocore head
• Submersible to 2,000
• Cores 2-4 diameter, up to 15 long
• VC head 150 lbs
• VC head full 15 core tube 300 lbs

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• Rossfelder P-5 vibrocorer
• 150 pounds
• 3,400 vpm
• Cores to 15 feet
• Less disruption of sediment column than push
  cores

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Vibrocoring from the R.V. Mudpuppy
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Vibrocoring from the R.V. Mudpuppy
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Vibrocoring from a Pontoon Boat
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Vibrocoring from a Zodiac
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Vibrocoring from john boats
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Vibrocorer suspended from boom truck
Corer head
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Core Sampling

• Core to refusal where possible
• In impoundments, try for original terrestrial soil

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Core Tubes

• 1/8, 4 OD Lexan tubing
• Polycarbonate resin
• Tougher than CAB, but more brittle
• Not easily cut into sections
• Available in other thicknesses diameters

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Core Tubes

• 3/32 thick, 4 OD cellulose acetate butyrate
  (CAB) tubing
• Easily cut into sections capped
• Available in other thicknesses diameters

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Core Catchers
From Wildlife Supply Co.
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Core Processing

• Processing
• Cut tube into sections, if necessary
• Open core tube
• Document core stratigraphy
• Collect sub-samples
• Can be done on sampling vessel or on shore
• On shore more people, but faster

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Fein Saw
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Opening tube with a Fein saw
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Subsampling the Core

• Plan ahead of time
• Consider necessary sample volume ( minimum
  sampling interval)
• Plan for field QC samples
• Usually field dups

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Documenting the Core

• Photographs
• Label in each photo
• Put measuring tape in photo
• Field Notes
• Color, texture, etc.
• Dont wear polarized sunglasses

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A word about Sediment Dating
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A word about Sediment Dating

• Lead-210
• t1/2 22.3 years
• Gone after 6-7 half-lives (130-160 years)
• Best in lake environments
• Often get confusing data collect multiple cores

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Toxicity Testing

• Done less often than chemical testing or
  biological communities
• Why do toxicity testing?
• Integrates effects
• Not affected by habitat quality
• Uses important food chain organisms
• Direct proof of effects
• No effect no pollution (?)

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Freshwater Bioassay OrganismsMidge larvae
Amphipod
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Toxicity Test Types

• Acute or Chronic
• Standardized by EPA, ASTM, Environment Canada
• Acute 10-14 days endpoints survival, growth
• Chronic 28-60 days endpoints survival,
  growth, reproduction

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Bioaccumulation Testing

• Three kinds
• Laboratory tests
• Field studies
• Caged organisms
• Resident organisms
• Models

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Bioaccumulation Testing

• Laboratory test aquatic oligochaete Lumbriculus
  variagatus
• 28 days
• Accumulation Factor (AF) conc. in worms
• conc. in sediment

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Bioaccumulation Modeling

• Simplest Equilibrium Partitioning Modeling

Lipids
Sediment Carbon
Interstitial Water
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Equilibrium Partition Modeling

• (Ctss/L) (Cs/TOC) x AF
• Ctss fish tissue conc. at steady state
• L fish tissue lipid content
• Cs sediment concentration
• TOC sediment total organic carbon
• AF biota/sediment accumulation factor (BSAF)

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More sophisticated bioaccumulation models

• Environmental properties
• Water temperature
• DOC, TOC
• Chemical characteristics
• Water concentration
• Sediment concentration
• Octanol-water partition coefficient (Kow)
• Species characteristics
• Lipid content
• Diet
• Life history food chain position

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Bioaccumulation Testing

• My preferred hierarchy
• Caged organisms laboratory studies
• Resident YOY fish
• Resident adult bottom-feeding fish, or other
  benthic organisms
• Models
• Always better to measure than to model

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Dam-Specific Effects Issues

• Lower water level turn aquatic problem into
  terrestrial problem
• Different toxicity bioaccumulation routes
  endpoints (species)
• Top predator now an eagle or mink instead of a
  fish
• Increase human exposure ?

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Data InterpretationSediment Quality Criteria

• Uses
• Evaluate sediment quality
• Establish cleanup objectives
• Assess suitability for open-water disposal
• Assess fill quality for shoreline development
• Agree to at start of project

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Chemical Concentration SQC

• Tied to biological effects
• Cu gt X ppm mortality in mayflies
• Usually tied to toxicity rather than
  bioaccumulation or changes in community structure
  or human health
• More often guidelines than regulations

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Database Chemical SQC
Presumed Toxic
PEC
Possibly Toxic
Increasing Concentration
TEC
Presumed Nontoxic
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Examples (mg/Kg DW)

• Chemical TEC PEC
• Total PCBs 0.06 0.68
• Total DDT 0.005 0.57
• Cadmium 0.99 4.98
• Lead 35.8 128
• Zinc 121 459

(McDonald et al., 2000)
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Wisconsin SQC Guidance

• Consensus-Based Sediment Qaulity Guidelines
  Recommendations for Use and Application Interim
  Guidance
• WT-732 2003
• Wisconsin DNR Contaminated Sediment Standing Team

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One Scenario
Additional sampling definitely required
PEC
Additional sampling/assessment may be required
Increasing Concentration
TEC
No additional sampling
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Wisconsin Midpoint Concentration Concern
Levels
Level 4
PEC
Level 3
MEC
Increasing Concentration
Level 2
TEC
Level 1
Use Levels to Rank Sites
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Other SQC

• Soil quality criteria
• Residential or Industrial land use
• PEC Resid. Soil Ind. Soil
• PCBs 0.68 4 16
• Copper 149 20,000 73,000
• Lead 128 400 900
• (mg/Kg DW)

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Dam-Specific SQC Issues

• Original native soil excavation depth
• Easy to determine excavation depth
• Concentrations cleanup criteria?

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Recon vs. Definitive Surveys

• Start with Recon Survey
• Limited number of samples
• Bulk sediment chemistry
• Compare to SQC
• Grain size organic carbon content

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Recon vs. Definitive Surveys

• Depending on results of Recon Survey, may
• No additional sampling
• Limited additional sampling, for chemistry
• Extensive additional sampling, for chemistry,
  toxicity, bioaccumulation

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Sediment Management Framework
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Complete Dam Removal Natural Erosion
Deposition

• Issue demonstrate transport deposition will
  not
• Cause long-term adverse physical habitat changes
  downstream or upstream
• Fill pools, bury riffles, etc. downstream
• Upstream channel incision
• Increase bioavailability of contaminants

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Staged Dam Removal Natural Erosion Deposition

• Issues
• Assess engineering suitability of dam for staged
  removal
• Assess impacts of water flows and sediment loads
  on downstream geomorphology and ecology
• (Plus issues for complete dam removal)

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On-Site Isolation or Capping

• Issue demonstrate that
• Capping will reduce contaminant availability to
  aquatic and terrestrial ecosystems, and humans
• Capping wont disrupt remaining ecosystem
• Decrease riparian zone, wetlands, bottomlands,
  etc.

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Partial Removal of Hot Spots

• Tasks
• Locate hot spots
• Remove dispose of sediment
• In the dry or wet
• Demonstrate that remaining sediment is nontoxic
• Post-remediation monitoring

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Sediment Removal Wet Dry
(HRC, Inc.)
(ECT, Inc.)
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Full Removal of All Sediment

• Tasks
• Identify extent of contaminated sediment, in 3D
• Characterize degree of contamination, for
  disposal decisions
• Remove dispose
• Post-remediation monitoring

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Contaminated Seds Run Away

• Long term bad idea
• Reservoir contaminant time bomb
• Combine dam hazard assessment with contaminant
  assessment?

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Post-Remediation Monitoring

• Sediment analyses
• Channel geometry substrate measurements
• Revegetation rate of former impoundment
• Fish macroinvertebrates
• Changes in recreational other social aspects
  and perceptions

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There is something fascinating about science.
One gets such a wholesale return of conjecture
out of a trifling investment of fact. (Mark
Twain, 1874)

• Objective optimize representativeness of our
  facts, to improve the quality of our conjectures